Junction capacitors can be produced with doped ferroelectric ceramics as dielectric. Although capacitors composed of said ceramics have a high capacitance, they also have a highly nonlinear dependence of the capacitance on the temperature and on the voltage present. The change in capacitance can be up to 80% in the case of some materials or rated voltage values. This is exploited in capacitors having capacitance values dependent on a BIAS voltage. In particular, it is thus possible to produce variable voltage-controlled matching circuits such as are required, e.g., in radio frequency (RF) technology.
Known dielectrics composed of ferroelectric materials are, e.g., barium titanate and strontium titanate with suitable additives. Capacitors composed thereof alter their dielectric constant with the size of the voltage present.
However, the ageing of these components is disadvantageous. The electrical values of the ceramic capacitors in these components, in particular the capacitance value thereof, change with time.
The ageing and hence the service life of these components are in this case greatly dependent on parameters such as present field strength, temperature, and proportion of oxygen vacancies in the material. Since the service life is an essential criterion for the usability of these components in RF circuits and in particular in the RF part of mobile telephones, it is necessary to find components and methods with which the hitherto unsatisfactory service life of these components can be increased.